The Marauder's Map is a magical document that reveals all of Hogwarts School of Witchcraft and Wizardry. Not only does it show every classroom, every hallway, and every corner of the castle, but it also shows every inch of the grounds, as well as all the secret passages that are hidden within its walls and the location of every person in the grounds, portrayed by a dot. It is also capable of accurately identifying each person, and is not fooled by animagi, polyjuice potions, or invisibility cloaks; even the Hogwarts ghosts are not exempted from this. The Map's only possible flaw lies in the fact that it cannot differentiate people who bear similar names (the shared names aren't given a Junior or Senior at the end). It can also reveal secret passages the Marauders found, though it only did this on one known occasion (in his third year, Harry Potter was shown how to use the statue of the humpbacked witch to enter Hogsmeade Village).

Fred and George Weasley

Fred and George Weasley "nicked" the map from Filch's office in their first year at Hogwarts. They had been taken to his Office for letting off a Dungbomb and saw a drawer marked Confiscated and Highly Dangerous. George dropped another Dungbomb, while Fred stole the Map from the drawer. They had to experiment with it in order to learn how to get it to work, but it gave them clues, "flickering into life here and there" when they came close to the activating phrase, until finally they got it exactly. Because of this map, the twins memorized the secret passageways of Hogwarts which they used for quite a few of their many pranks. [1] In Harry Potter's third year at Hogwarts Fred and George (probably out of gratitude for Harry saving their sister the previous year) gave the map to Harry, so that he could go to Hogsmeade on the weekends, although he had not obtained a permission slip to do so from his guardians, Vernon and Petunia Dursley.

"Mr. Mooney presents his compliments to Professor Snape and begs him to keep his abnormally large nose out of other people's business.Mr. Prongs agrees with Mr. Mooney and would like to add that Professor Snape is an ugly git.Mr. Padfoot would like to register his astonishment that an idiot like that ever became a Professor.Mr. Wormtail bids Professor Snape good day, and advises him to wash his hair, the slime-ball."

Harry used the Map throughout his time as a student at Hogwarts, especially during his third year, when he tried to find his way into Hogsmeade. Then, he used the One-Eyed Witch Passage which led into Honeydukes cellar. The map however will insult anyone who doesn't know how to activate it. Professor Remus Lupin did catch Harry with the map (after Snape found it while interrogating Harry), and subsequently confiscated it, surprising the younger wizard with his knowledge of how to activate it. It was through the map that the professor discovered Peter Pettigrew was still alive, leading him to conclude it was indeed the latter that had betrayed Harry's parents, in the process framing their old friend Sirius Black for the crime. This would go a long way towards repairing the rift between the two co-creators of the map. He would return the map to Harry before leaving Hogwarts, at the end of the year.

During Harry's sixth year, when he spent a great deal of time obsessing over Draco Malfoy's daily activities, he used the map often.

When monitoring Draco Malfoy, Harry found he often disappeared off the map. The cause of this was not revealed until after he asked Dobby to trail Draco to find out what he was doing when he disappeared off the map. Dobby discovered that Draco was disappearing into the Room of Requirement, which was not on the Marauder's Map. Whether because it was Unplottable or the Marauders never found the room is unspecified.

While on the run in looking for Horcruxes, Harry would often look at the map to see what Ginny Weasley, his love interest, was doing, which would hint that the map works from any location.

Use

The map activating from its blank mode to map.

The map is normally disguised as a blank piece of parchment. To view the map, one must tap it with one's wand and recite, "I solemnly swear that I am up to no good." The content of the map will reveal itself.

To hide the contents of the map so the parchment appears blank again, one must again tap it and recite, "Mischief managed."

If someone tries to view the map without reciting the proper incantation, the map merely insults them and tells them to mind their own business. Severus Snape experienced this phenomenon when he tried to view the map by force.

An added bonus is that if the bearer of the map approaches the entrance to a secret passage protected by a password, the password will appear on the map (usually as a speech bubble that appears close to the dot representing the Map's holder).

Exceptions to Use

In some rare cases, the map may not be used to the best of its ability. Heading out through the secret passage from the Whomping Willow to the Shrieking Shack will make the person disappear, as Snape mentions in the spring of 1994, so the Shrieking Shack is not included on the map because it goes off the edge of the map. It also does not show any person that may be inside the Room of Requirement, as the Room of Requirement is unplottable and it itself does not show up on the map, or the Chamber of Secrets, as it is very unlikely that any of the creators of the map knew of its existence at the time that the map was made.

Additionally, the map does not differentiate between two people with the same name. This was the case with Barty Crouch Jr., who was simply shown as "Bartemius Crouch" on the map (instead of Bartemius Crouch II/Junior). This lead Harry Potter to believe that Barty Crouch Sr. was in Hogwarts, when he was actually at his own home at the time.

Similarly, it identifies animagi by their actual name even when they are in their transformed state. It was by this mechanism that Lupin was able to identify Peter Pettigrew 's presence at Hogwarts despite being presumed dead.

Behind the scenes

According to J. K. Rowling, Harry never gave the map to Teddy Lupin or any of his children, but his son James probably stole it from Harry's desk.

The magical defences on Hogwarts have been mentioned several times, including Hogwarts being unplottable. That implies that mapping Hogwarts is impossible, which is exactly what the Marauder's Map does. There are some possible loop holes for this: for example, making a place unplottable might simply make it impossible for it to be mapped with reference to somewhere else. As the Marauder's Map only covers Hogwarts, not of its position relative to (for example) London, it would circumvent the theoretical unplottable charm.

The claim that the map shows "every" corner of Hogwarts is likely an exaggeration, as there is no indication that it shows the Chamber of Secrets or the Room of Requirement. However, the map was created based on the Marauders' knowledge of Hogwarts and as none of them were Parselmouths, they would not have been able to access the Chamber of Secrets. Considering that Fred and George had it during the opening of the Chamber of Secrets, and the disappearance of their sister into it, it seems very unlikely it showed the Chamber or they would have mentioned it. Also, it is possible that they did manage to find the Room of Requirement, but that the room itself is unplottable as need be [4]. However, it is not very likely the Marauders did discover the Room of Requirement as Sirius never suggested the Room to Harry as a possible location for the meetings of Dumbledore's Army in Order of the Phoenix. It is also possible that Sirius didn't think about the Room of Requirement at the time.

In the book, the map is described as a single piece of parchment that could be laid on a desk in a classroom. In the film, the map is shown as a rather large, much-folded paper with several unfolding flaps within it. This is actually more practical, as it is unlikely that all of Hogwarts—having many floors and towers—could be drawn on a single piece of paper.

Harry retrieved the Marauders Map when Barty Crouch Jr. took it, by simply taking it from the fake Moody's office at the end of the school year. (Rowling had forgotten to mention it.) [5]

Also in the film adaptation of Harry Potter and the Prisoner of Azkaban, while Albus Dumbledore is pacing in his office, his name is spelt Albvs Dvmbledore. This was most likely done simply to give the impression of age. During the late middle ages, 'v' and 'u' were used interchangably, with 'v' always appearing at the beginning of a word and 'u' always appearing in the middle or at the end of a word.